American Expeditionary Force

The American Expeditionary Force was a c. 4,000,000-strong force sent to Europe during World War I by the United States, who fought alongside the Allied Powers during the 1918 Spring Offensives and the Hundred Days Offensive. They were a large force of inexperienced young men commanded by General John J. Pershing, an old and experienced commander who led them into many bloody engagements. They suffered 320,000 casualties during the war, with 63,114 (the majority of the losses) of them dying of non-combat causes such as the Spanish Influenza.

History
The United States prepared a 4,000,000-strong army to assist the British and French forces fighting Germany on the Western Front of World War I on May 3, 1917, and 2,000,000 of their number arrived in France almost exactly a year later. Their first battle was the Battle of Belleau Wood, in which they proved their ferocity but also their crippling inexperience, as the US 2nd Marine Battalion swept across an open field in the sights of German machine gunners. The AEF suffered extremely heavy losses again at St. Mihiel and the Meuse-Argonne Offensive, but in the latter (August-November 1918) they were able to push so far that Germany had to sign an armistice to prevent an invasion of Germany itself. Not only did the AEF fight in France, but some units were dispatched to northern Italy at the Piave River to assist the Italian Army and some other Allied units in fighting against the Austro-Hungarians and Germans on the Isonzo River. After the armistice of 11 November 1918, the AEF had turned from inexperienced boys into a modern and professional army.